A. Field of the Invention
This invention relates generally to the field of firearms. More particularly, the invention relates to a rotary magazine for a firearm that contains a mechanism for holding the bolt of the firearm in an open position after the last cartridge in the firearm has been fired and the bolt has recoiled, thereby signaling to the user that the magazine is empty. The invention is applicable to bolt-action, manually operated firearms, semi-automatic firearms, and fully automatic firearms.
B. Description of Related Art
It is known in the art to provide a hold-open feature by which the bolt remains in an open position after the last shot in a magazine has been fired. The purpose of the hold-open feature is to alert the user of the need to re-load the weapon, and to avoid an unnecessary and annoying attempted firing of the weapon when in fact the magazine is empty. Representative patents describing hold-open features include Roemer, U.S. Pat. No. 2,321,045; Ruger et al., U.S. Pat. No. 3,846,928, Ruger, U.S. Pat. No. 4,438,678, Smith, U.S. Pat. No. 4,594,935 and Johnson, U.S. Pat. No. 2,341,869.
The Johnson rifle described in the ""869 patent is a rotary magazine semi-automatic weapon which saw limited duty in WW II. The Johnson rifle is also described to some extent in the publication Firearms Assembly 1, The NRA Guidebook to Shoulder Arms, pp. 144-145, published in 1972 by the National Rifle Association. The rifle includes a hold-open feature, however the hold open feature is a rather complex arrangement of mechanical parts that involve both on the rifle body and the magazine. As such, the design is not one suited to wide applicability, or suited to the situation in which a magazine is modified to provide the hold open feature and no other modifications are needed to the rest of the firearm.
It is the belief of the present inventor that many, if not most, rotary magazines for semi-automatic firearms do not contain a hold-open feature. One of the most popular of such firearms is the Ruger(copyright) 10-22-caliber semi-automatic rifle. Adding a hold-open feature to those firearms with rotary magazines that presently do not have a hold open feature would certainly improve the performance and overall experience in using the firearm. However, the addition of a hold-open feature, in which no modifications are made to the rest of the firearm, is a difficult design in which there certainly is no obvious solution. To see why this is the case, the magazine of Ruger(copyright) 10-22-caliber semi-automatic rifle will be briefly described.
Referring now to FIGS. 1-3, the factory or stock rotary magazine 10 for a Ruger(copyright) 10-22 semi-automatic rifle is shown isolated from the rest of the firearm. In FIG. 1, the magazine is shown in a perspective view looking down on a feed insert 12 and the magazine housing 14. The feed insert 12 is a metal piece that receives the cartridges when they are inserted into the magazine. The feed insert has a flat planar surface 15 that the bolt slides over when the firearm is fired. A rotor 16 is positioned inside the magazine housing. The rotor 16 has a series of projecting ridge elements circumferentialy spaced about the shaft of the rotor that accommodate or receive the individual cartridges when the cartridges are inserted into the feed insert. A biasing spring (not shown) tends to bias the rotor in a clockwise direction as viewed from the rear of the magazine to move the cartridges to a firing position at the top of the feed insert. When the user inserts the cartridges, the force accompanying insertion the cartridge into the feed insert 12 past overcomes the force of the biasing spring, allowing the rotor 16 to rotate in a counterclockwise direction and receive the individual cartridges between the ridge elements of the rotor. One of the projecting ridges is slightly larger than the rest and is used to move the last cartridge up into firing position; this ridge 18 is shown in FIGS. 1 and 2. The last cartridge is held up in position by the rearmost portion 18A of the ridge 18 by a wedging action. This wedging action also prevents further rotor rotation until the cartridge is pushed forward or removed in the improved magazine of this invention.
The unaltered, factory stock magazine of FIGS. 1-3 holds ten rounds of 0.22 caliber long rifle ammunition. Each of the ten rounds is stripped off the magazine 10 and pushed forward into the rifle chamber and fired until the magazine is empty. The force of the rotor""s biasing spring keeps each cartridge in turn jammed up into the feed insert""s feed lips 20 in position for firing. The tenth round (last cartridge) relies upon the rearmost portion 18A of the top portion of the ridge 18 to position it between the feed lips 20 in position for firing.
After the last shot is fired, the rotor is stopped from further rotation by interference between the ridge 18 and the feed insert at the location 24 shown in FIGS. 1 and 2. No further rotation is possible due to this mechanical interference. The design of the factory magazine was to intentionally prevent any further rotation to allow ease of loading of the first cartridge, i.e., insure sufficient space between the top of the rotor and the side of the feed insert to allow the first cartridge to be inserted into the magazine.
The magazine of FIGS. 1-3 has no features to hold the rifle bolt open after the last shot has been fired. It is an object of the invention to provide modifications to a rotary magazine of the general type shown in FIG. 1 to provide such a hold-open feature. Another principal feature of this invention is that the hold open feature is completely provided by the magazine, and as such does not require any modifications whatsoever to the firearm per se.
A rotary magazine is provided for a firearm having a bolt that reciprocates between an open position and a closed, firing position, in which the magazine includes features to hold the bolt in an open position after the last shot has been fired. The hold open features are provided entirely in the magazine, and no modification is needed to the firearm. While the rotary magazine of the present invention is particularly suitable for a semi-automatic firearm, such as the Ruger(copyright) 10-22-caliber semi-automatic rifle and magazines of similar design, and while the following text and accompanying figures describe various embodiments of a rotary magazine for that rifle, it will be appreciated that the scope of the invention encompasses other types of firearms having rotary magazines.
The inventive rotary magazine with the hold-open feature includes a magazine housing adapted for containing a plurality of cartridges. A feed insert is carried by the housing and has a planar surface along which the bolt travels when reciprocating between the closed and open positions. A spring-loaded rotor is contained within the housing that has a shaft rotating about an axis. The rotor advances the cartridges one by one to a firing position in the feed insert.
A hold-open lever is positioned within the magazine adjacent to the planar surface of the feed insert. The hold-open lever has a first position in which the lever is in an aligned condition relative to the planar surface of the feed insert, and a second or deployed position in which the lever is in a non-aligned condition relative to the planar surface. In the second position, the lever blocks movement of the bolt from the open position to closed position, holding the bolt open.
The shaft of the rotor carries a trip mechanism. The trip mechanism is provided as a means for moving the lever from the first position to the deployed position after the last shot has been fired. In particular, when the last cartridge is fired and the bolt has recoiled to the rear of the magazine, the rotor is permitted to rotate an additional amount (typically between 10 and 15 degrees), and this additional rotation allows the trip mechanism to contact the hold-open lever and thereby actuate the hold-open lever and cause it to move (e.g., by rotation or linear translation) to the deployed position in which it blocks forward movement of the bolt. Thus, the bolt is held in the open position.
The following specification describes numerous embodiments of the hold-open lever, trip mechanism, rotor, and feed insert which are designed to allow the rotor to rotate an additional amount past its nominal, original position after the last shot has been fired, and thereby allow the trip mechanism to actuate the hold-open lever. In some of the embodiments, the feed insert is provided with a recess or void region to accommodate the rotor to allow such additional rotation. In other embodiments, the rotor is formed with a recess or void so that it does not interfere with the feed insert, permitting the rotor to rotate an additional 10 to 15 degrees after the last shot has been fired.
Additionally, several different configurations of a trip mechanism and hold-open lever are described. In some embodiments, the hold-open lever pivots about a lug formed on the side of the feed insert, and the trip mechanism comprises a small stud attached to the shaft of the rotor. When the rotor rotates that additional 10 to 15 degrees, the stud contacts a portion of the hold-open lever. This contact and associated rotation of the shaft of the rotor causes the hold-open lever to pivot about the lug such that a second portion of the hold-open lever is moved to the blocking position, holding the bolt is the open condition. In yet further embodiments, the hold-open lever is designed such that the action of the trip mechanism causes the hold-open lever to move in a linear fashion. In particular, the hold-open lever is actuated from a depressed position to an extended position. In the extended position, a portion of the hold-open lever is moved into an obstructing position relative to the path of the bolt, holding the bolt in an open condition.
In another aspect, a method is provided of improving (e.g., modifying) a rotary magazine for a firearm such that the magazine provides a hold-open feature. The magazine has a rotor, a feed insert and a magazine housing for containing a plurality of cartridges. The method is particularly suitable for either retrofit modification of an existing magazine (such as the Ruger(copyright) 10-22-caliber semi-automatic rifle) or, more preferably, used in the design and manufacturing of new magazines for the firearm.
The method involves forming the rotor and/or feed insert so as to enable the rotor to further rotate relative to the feed insert beyond a nominal original position after the last cartridge in the magazine has been fired and the bolt moves to the rear, with such further rotation occurring without interference or binding between the rotor and feed insert. The method further includes the step of incorporating a hold-open lever into the magazine to block forward motion of the bolt and retain the bolt in an open position. The method further includes the step of providing an actuating mechanism for the hold open lever. Several different types of actuating mechanisms are described herein. The actuating mechanism is responsive to the further rotation of the rotor relative to the feed insert to thereby move the hold-open lever into a position to block the forward motion of the bolt after the last cartridge in the magazine has been fired and the bolt moves to the rear.
As described in detail herein, the rotor and/or feed insert can be formed in a manner in which voids or recessed regions are formed so as to allow the additional rotation past the nominal original position to occur. In a preferred embodiment, a portion of the feed insert is removed. The feed insert includes a pair of feed lips or cartridge aligning features to maintain proper alignment of the cartridge with respect to the feed insert. However the preferred modification to the feed insert leaves such aligning features intact.
These and many other details of presently preferred and alternative embodiments will be more apparent from the following detailed description and the appended drawings.